‎"HERSCHEL, WILLIAM.‎
‎Description of a Forty-Feet Reflecting Telescope. - [HERSCHEL'S FAMOUS 40-FOOT TELESCOPE]‎

‎London, Peter Elmsly, 1795. 4to. In recent marbled paper wrappers. Extracted from ""Philosophical Transactions"". Including title-page of volume. Leaves reinforced in margin. Light offsetting from folded plates as usual. Plate depicting the full telescope with professional repair to lower right corner. (4), 347-410 pp. + 19 folded plates.‎

Reference : 57071

‎First appearance of William Herschel account of his great 40-foot telescope. It was the largest telescope in the world for 50 years and it was possibly used to discover Enceladus and Mimas, the 6th and 7th moons of Saturn. The plate of the 40-foot telescope fully assembled remains as one of the great icons of astronomy. ""It is well known that King George III granted £2,000 for the construction of the 40-foot reflector, and that this was supplemented by a further £2,000 plus other expenses. Only recently has it become evident that the second grant was made in the context of a serious row between monarch and astronomer. Herschel was of course in uncharted territory in attempting the construction of such a monster. The king had understood that the first £2,000 was the total required, and when this proved not to be the case he may well have suspected Herschel of deliberately underestimating the costs involved when making his original application. Although the king acceded-reluctantly-to the second request, from then on Herschel was required to account for every last penny of expenditure, and was told in no uncertain terms that no further grant would be forthcoming.The 40-foot reflector proved cumbersome and its results did not justify the labor and cost of its construction. What has only recently been appreciated is the extent to which it became a millstone around its creator's neck. From Herschel's point of view, it lost its principal raison d'être in 1790 when an observation with the 20-foot convinced him of the existence of ""true nebulosity."" But to the king it was an enduring symbol of his patronage of science, and visitors to Windsor Castle were invited to make the short journey to Slough to see the world's biggest telescope."" (DSB)‎